Tubular skylights have been provided for illuminating rooms inside buildings with natural light. Not only do tubular skylights thus save electricity and, concomitantly, are environmentally benign, but they illuminate rooms in a pleasing way using natural sunlight instead of 60 cycle electric light. An example of a commercially successful tubular skylight is disclosed in U.S. Pat. No. 5,099,622, assigned to the same assignee as the present invention and incorporated herein by reference.
A tubular skylight includes a roof-mounted, dome-like transparent cover. The cover is mounted on the roof of a building by means of a flashing. An internally reflective tube depends downwardly from the roof to the ceiling of the room sought to be illuminated, and the bottom of the tube is covered with a disk-shaped light diffuser that is positioned at the ceiling. The round cross-sectional shape of the tube promotes light reflectivity and transmission down the tube, into the building.
In most existing tubular skylights, the ceiling dry wall supports the diffuser and the tube. To install a tubular skylight, a circular hole is cut in the existing ceiling dry wall and another hole is cut in the roof, and then the skylight positioned and mounted as described above.
The present invention recognizes that tubular skylights can be used in applications other than in conventional ceiling dry walls. For example, the present invention recognizes that tubular skylights can be used to illuminate relatively larger buildings that have ceilings defined in part by rectangular grids of metal support joists. The grids are used to support rectangular-shaped ceiling panels.
As understood by the present invention, the bottom portion of a tubular skylight should be shaped complementarily to the ceiling opening with which the skylight is engaged. In the case of conventional ceilings made of dry wall, the ceiling opening is formed to accommodate the round cross-sectional shape of the skylight. In the case of larger ceilings having rectangular support grids, however, the opening with which the skylight must be engaged, namely, one of the rectangular areas formed by the grid, is not designed with tubular skylights in mind, but rather with the rectangular shape of conventional ceiling panels in mind. As intimated above, this problem cannot be solved simply by making the skylight parallelepiped-shaped, because a skylight with a rectangular cross-section will not transmit light down to the ceiling as efficiently as will a tubular skylight. Moreover, the tubular shape of skylights is widely accepted and indeed ingrained in the industry. The present invention has both recognized the problem of installing skylights in a ceiling grid, and provides the below-disclosed solution.